CHICAGO (FRONTLINE MEDICAL NEWS) – The biosimilar trastuzumab antibody MYL-1401O is comparable in safety and efficacy to the FDA-approved trastuzumab (Herceptin) in women with HER2-positive advanced breast cancer, finds a phase III trial reported at the annual meeting of the American Society for Clinical Oncology.

Objective response rates at 24 weeks, the primary endpoint, were 69.6% with MYL-14010 compared to 64% with trastuzumab, reported lead author Dr. Hope Rugo of University of California, San Francisco.

A total of 500 patients with metastatic HER2-positive breast cancer were randomized in the Heritage trial to receive taxane chemotherapy with either trastuzumab or MYL-14010 for at least 8 cycles, followed by trastuzumab alone until disease progression. Response rates were assessed at 24 weeks and 458 patients were evaluable. Patients were enrolled at 95 centers in Asia, Latin America, Africa, and Europe.

Safety was comparable between the two arms; 38.1% of patients receiving MYL-1401O and 36.2% of patients receiving trastuzumab experienced at least one serious adverse event. There were four treatment-related deaths in each arm. Neutropenia was the most common adverse event.

“The Heritage study has demonstrated efficacy equivalence between the trastuzumab biosimilar MYL-1401O [and] Herceptin in combinations with taxanes as first-line therapies for HER2-positive metastatic breast cancer at 24 weeks. We also demonstrated similar safety, immunogenicity and pharmokinetics. This proposed biosimilar has the potential to meet the need for an affordable treatment option with HER2-positive breast cancer,” Dr. Rugo said.

She also said that she would readily adopt MYL-1401O as an alternative once it gains FDA approval.

Mylan, makers of MYL-14010, funded the study. Ten investigators reported serving in advisory roles for, having ownership or stock interest in, or receiving financial compensation or honoraria from multiple companies, including Mylan.

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